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Ill! 6 2 Sheets-Sheet 1 L. THOMAS COMPUTING MACHINE Filed Oct. 16. 1924March 6, 1928.

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L. THOMAS COMPUTING MACHINE 2 Sheets-Sheet 2 Filed 001:. 16. 1924 IHIIIIIN V EN TOR.

6 A TTORNEY mama Mar. 6, 1928.

UNITED STATES PATENT OFFICE LUCIE TEOIAS, OI NOWAWEB, BY POTSDAI,GEBIANY; LUCIE mun, uh m ABSIGNOB '10 am BEBGIANN, OI BERLIN, Gm.

COMPUTING MACHINE.

Application fled October 18, 1924, Serial No. 748,896, and in GermanyNovember 17, 1983.

The resent invention relates to improvements 1n computing machineshaving reciprocatory sliders. I.

The principal object of the invention is to provide a compact,light-weight device suitable for both addition and subtraction.

Another object of the present invention is to-provide a simple andimproved signal arrangement to show the operator when a l slider hasbeen operated past the zero position, whether during addition orsubtraction, so that proper steps may be taken to obtain the correctresult.

The invention also comprehends an improved guiding plate for thesliders,and an improved slider, each of which are preferably made fromsheet metal.

Furthermore the invention contemplates a machine which is readilyconvertible for adding or subtracting as desired. To this end, the faceof the machine has a reversible flap provided on one side with part ofthe means used for an operation in addition and on the other side withpart of 'the means used for an operation in subtraction. The front plateof the machine is provided with the remaining parts necessary forcarrying out either of these operations at will, the unnecessary indiciaand slots for one operation being covered by the flap in one position,and those for the other operation being covered by the flap in the otherposition.

Another object of the invention is to provide an operating pencil forthe machine with suitable means, as clips, for removably fastening it tothe side of the machine to clamp the reversible flap in place so thatthe entire device may be readily inserted into a carrying case.

The accompanying drawings show a convenient embodiment of the machine,it being understood that the drawings are merely illustrative of theinvention rather than limiting the same, for the invention may beembodied in various forms.

In these drawings:

Fig. 1 is a front elevation of the machine showing a portion of thereversible flap broken away to reveal the front numbering on the plateand showing other portions of the flap in position for addition or forsubtraction;

Fig. 2 is a vertical section taken on the line 2 of Fig. 1;

I rearwardly exten Fig. 3 is a horizontal section taken on the line 30fFigs. 1 and 2; t

Fig. 4 is a front elevation with parts of the front plate broken awayand certain of the sliders removed;

Figb is a fragmentary perspective view of Is, slider; i

ig. 6 is a fra mentar ers ctive view of the back-plate? y p pe I F lgs.7 and 8 are fragmentary views showng the sliders in their extremeposition, illustrating the giving of signals when the slider has beenmoved beyond the 9 and 0 positions respectively; and I Fig. 9illustrates a modified back-plate.

As here shown, the machine is in the form of a flat compact devicepreferably made up almost entirely out of sheet metal and capable ofbeing carried in the pocket.

A rear platelO of sheet metal is provided with forwardly bent edges 11,12, 13, and 14, while a front (plate 15 is provided with ing sideflanges 16 and 17 and an end flange 18. These flanges are bent uponthemselves as shown at 19 so as to he behind the rear plate 10. The twoplates are locked in place by inwardly bent prongs 20, and when disposedas has been described provide a chamber 21 for the enclosed operatlngparts of the machine.

The front plate is punched to provide a plurality of parallel slots 22,a completeslot being shown to the left of the center of Fig. 1. Theupper and lower ends of 22 and 22" of these slots are extended'laterallyto the left as shown, and they are preferably then continued in the formof short slots 23 and 24 connected with the lateral extensions andextend toward one another parallel with the main portion of the slot 22,thereby provlding return extensions for purposes to be hereafterdiscussed. If desired, one may remove the narrow strip of materialbetween the main part of the slot and the short slots.

Above each of the slots 22 and about half way between the slots 22 andthe adjacent return slots 23, the front plate is providedwith inspectionopenings 25 to observe the sliders 26 carried in the chamber 21.

These sliders are shown more in detail in Figs. 4 and 5 and arepreferably made out of a strip of sheet metal by bending backwardly aseries of prongs 27. The removal of the prong material; from the body ofthe flat sheet from which the slider is stamped rovides the slider withserrated lateral e ges 28 and 29, these edges comprising a number ofteeth 28' and interposed notches 27 and at the same time provides aguide-way or channel 30 for the slide, the side walls of the guide-Waybeing serrated on account of being made up of a number of rearwardlybent prongs. The lateral edges 28 and 29 of the sliders are here shownas being provided with twenty-two notches 27, notches being disposed atthe bottom or lower end of the slider and teeth 28' at the upper end ofthe slider. The twelve teeth on the upper left hand side of the slidersare preterably colored so as to present a contrasted appearance relativeto the other teeth on the slider, this coloring being indicated in Fig.4: of the drawing by shading these teeth. The sliders are provided withthe digits 9, 8, 7, 6, 5, 4, 3, 2, 1,0, between the upper notches, the 9being placed at the upper end of the slider.

Intermediate the back-plate 10 of the machine and the sliders 26 thereis provided a guide plate 31 also preferably made of sheet metal. Thisplate is here shown as being provided with a plurality of spring fingers32 struck out from the front face of the guide plate and integraltherewith. The

fingers are arranged in pairs, one finger be ing above and the otherbelow the center of the plate. This provides two rows of fingers, thefingers in one row being in alignment with the corresponding fingers ofthe other row so as to provide guides for the sliders 26 which may beplaced on the guide plate as indicated in the drawings. The rearwardlydirected prongs 27 on the slider are adapted to embrace the springfingers struck out from the guide plate and the fingers urge the sliderstoward the front plate 15 of the machine.

The front plate 15 is provided near the center of the machine withforwardly bent projections 33 and 34 preferably struck out from thematerial of the plate. These projections are preferably placed in linewith the 5s on the front plate and provide a pivotal mounting for areversible flap 35. The flap may, of course, be mounted in any otherconvenient manner. This flap is provided with a number of parallel slots36 spaced in the same manner as the slots 22 and so located as to be inline with these slots. The slots 36 open toward the edge of the flap 35adjacent its pivotal mounting, and the digits 4, 3, 2, 1, O, are placedon e ther side of the flap as indicated in Fig. 1. The flap is alsoprovided with a number of inspection openings 37 which are adapted to bedisposed over the inspection openings 25 in the front plate of themachine when the flap is moved up as indicated at the left of Fig. 1. Itwill be noted from inspection of the Fig. 1 that when the flap is down,

(as shown at the right) the digits 9, 8, 7,

6, 5, 4, 3, 2, 1, 0, appear alongside the straight slot made up of theslots 22 and 36,

of addition and multiplication, this being indicated by the plus sign atthe left of the flap and the sign of multiplication at the right edge ofthe flap.

When the flap is moved upwardly (as shown at the left of Fig.1), thedigits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, appear alongside the straight slot,and the upper return extensions 2223 have been covered by the flap. Themachine is now in condition for carrying out operations of division andsubtraction. Subtraction is indicated by a minus sign at the left of theflap and by the sign of division at the right.

In carrying out an operation in addition, the flap is moved to the lowerposition and the sliders are all brought to a position to bring thezeros behind the inspection openings 25. This may be readily broughtabout by pulling upwardly on the exposed end 38 of a wire loop 39 whichextends inside the chamber 21 in the manner shown to bring it below thelower end of the sliders. Stops 40 are provided to limit the upwardmovement of the loop so as to bring the zeros on the sliders up to theinspection openings. The sliders are then manipulated in the customarymanner, the uncolored teeth in dicating that the slider is to be moveddown while the colored teeth indicating that the slider is to be movedupward and that the pointer 41 is to be carried along the lateralextension 22 and down the short slot 22 thereby advancing the nextslider to the left one digit. The same movements are to be made eventhough the material between the slots and 23 were removed as iscustomary in some machines of th s type.

In carrying out certain problems, such. for example, as when the slideris in a position to bring the 9 behind the inspection opening and theslider to the right is to be moved up, and the addition completed bycarrying the pointer around into the short slot 23, the slider would bemoved so that the 9 goes below the inspection opening. One would thennotice the disappearance of the slider, or the appearance of theguiding-plate behind the inspection opening. This condition isillustrated in Fig. 7, and the operator should change the sliders in apredetermined manner to indicate the correct result. He should insertthe pointer into the notch in this slider adjacent the O in the nextslot to the left, moving up to the 0 position and then carrying theadjacent slider down one step by moving the pointer around the returnextension in the usual manner.

In carrying out certain problems in subtraction, wherein a slider hasits 0 in front of an inspection opening and the next slider to the rightis to be moved downwardly, one would, in carrying the result over intothe next column, move the former slider from the 0 position to theposition bringing the blank space behind the inspection openings 37-25,as indicated in Fig. 8. This indicates to the operator that he shouldinsert the pointer in the notch adjacent the 0 in the first mentionedslider, and move the pointer down and around the return extension 22"24.

In the event that one has pushed the slider up when it should have beenpulled down, the zero on the slider will be moved beyond the inspectionopening and the blank space will come to view. This will indicate to theoperator that he should have pulled the slider down. The error may berectified by moving the slider down.

The layout of the machine is preferably such that the sliders cannot bemoved beyond the signaling positions above described. This is readilybrought about by making the space between the ends of the sliders 'andthe body of the machine of the proper length to so limit their motion.

The extreme left slider 26 may, if desired, be provided with digitswhich contrast with those on the other sliders.- This may readily bedone by making different shaped figures or by making them out of aseries of dots such as shown.

As machines of the type above described may conveniently be carried in apocket case by being slid into the open end thereof, and in order tokeep the pointer with the machine, the present pointer is provided witha pair of spring clips 42 adapted to engage the front and back of themachine. These clips will hold the pointer in place, and at the sametime will hold the flap 35 close to the front plate of the machine inwhichever position it may be. v

In Fig. 9 I have illustrated a modified back-plate which functions as aguide plate. Here the fingers of Fig. 6 are replaced by similarlydisposed ridges pressed out of the back-plate itself.

It is obvious that the invention may be embodied in many forms andconstructions, and I wish it to be understood that the particular formshown is only one of the many forms. Various modifications and changesbeing possible, I do not limit myself in any way wit-h respect thereto.

What is claimed is:

1. A computing machine having a plurality of parallel reciprocatorysliders having serrated lateral edges and the digits, 0,

1, 2, 3, 4, 5 6, 7, 8, 9 thereon, and a front plate covering the slidersand having parallel slots each permitting access to eleven notches onone serrated edge of one slider, each end of each of the slots beingprovided with return-extensions to expose two notches on the otherserrated edge of the adjacent slider, the front plate having the digits9, 8, 7, 6, 5, 6, 7, 8, 9 alongside each slot.

2. In a computing machine, the combination with a plurality of parallelreciprocatory sliders having serrated lateral edges and the digits, 0,1, 2, 3, 4, 5, 6, 7, 8, 9 thereon, and a front plate covering thesliders and having parallel slots each permitting access to elevennotches on one serrated edge of one slider, each end of each of theslots being provided with return extensions to expose two notches on theother serrated edge of the adjacent slider, of a pivotally mountedreversible flap adapted to cover the return extensions at either end ofthe parallel slots.

3. In a computing machine, the combination with a plurality of parallelreciprocatory sliders having serrated lateral edges and the digits, 0,1, 2, 3, 4, 5, 6, 7, 8, 9 thereon, and a front plate covering thesliders and having parallel slots each permitting access to elevennotches on one serrated edge of one slider, each end of each of theslots being provided with return extensions to expose two notches on theother serrated edge of the adjacent slider, the front plate having thedigits 9, 8, 7, 6, 5, 6, 7, 8, 9 alongside each slot, and a pivotallymounted reversible flap adapted to cover the return extensions at eitherend of the parallel slots, the flap having open ended slots to permitaccess to the slots in the front plate and having the digits 4, 3, 2, 1,0, alongside the slots with the 4s adjacent the open end of the slots.

4. In a computing machine, the combination with a plurality of parallelreciprocatory sliders having serrated lateral edges and the digits, 0,1, 2, 3, 4, 5, 6, 7, 8, 9 thereon, and a front plate covering thesliders and having inspection openings for observing the digits on thesliders and parallel slots each permitting access to eleven notches onone serrated edge of one slider, each end-of each of the slots beingprovided with return extensions to expose two notches on the otherserrated edge of the adjacent slider, of a pivotally mounted reversibleflap adapted to cover the return extensions at either end of theparallel slots, the flap being provided with inspection openings adaptedto register with the inspection openings on the front plate when theflap is in one position.

5. In a computing machine, the combination with a plurality of parallelreciprocatory sliders having serrated lateral edges and the digits, 0,1, 2, a, 4, 5, s, 7, s, 9 thereon,

and a front plate covering the sliders and having inspection openingsfor observing the digits on the sliders and having parallel slots eachpermitting access to eleven notches on one serrated edge of one slider,each end of each of the slots being provided with return extensions toexpose two notches on the other serrated edge of the adjacent slider,the front plate having the digits 9, 8, 7, 6, 5, 6, 7, 8, 9 alongsideeach slot, of a pivotally mounted reversible flap adapt ed to cover thereturn extensions at either end of the parallel slots, the flap havingopen ended slots to permit access to the slots in the front plate andhaving the digits 4;, 3, 2, 1-, 0, alongside the slots with the lsadjacent the open end of the slots, the flap being provided withinspection openings adapted to register with the inspection openings onthe front plate when the flap is in one position. I

6. in a computing machine, the combination with a plurality of parallelreciprocatory sliders having serrated lateral edges and the digits, 0,1, 2, 3, 41-, 5, 6,

'2', 8, 9 thereon, and a front plate covering the sliders and havingparallel slots each permitting access to eleven notches on one serratededge of one slider, each end of each of the slots being provided withreturn extensions to expose two notches on the other serrated edge ofthe adjacent slider, the front platehaving the digits 9, 8, 7, 6, 5, 6,7, 8, 9 alongside each slot, of a pivotally mounted reversible flapadapted to cover the return extensions at either end of the parallelslots, the flap be-= ing pivoted in line with the 5s on the front plate,

7. it, computing machine having a front plate provided with parallelslots, each end of each slot being provided with return extensions andhaving the digits 9, 8, 7, 6, 5, 6, '2', 8, 9, alongside each slot.

8. it, reversible flap for computing machines, said flap having aplurality of slots extending inwardly from one side edge, and having thedigits at, 3, 2, 1, 0, alongside the slots.

9. A reversible flap for computing machines, said flap having aplurality of slots extending inwardly from one side edge, and having thedigits 4:, 3, 2, 1, 0, alongside the slots on both faces of the flap,the 4s being adjacent the open end of the slots.

10. it reversible flap for computing machines, said flap having aplurality of slots extending inwardly from one side edge, and having thedigits 4t, 3, 2, 1, 0, alongside the slots, the flap being furtherprovided with inspection openings adjacent the closed ends of the slots.

11. in a computing machine, a reversible flap having a plurality ofslots extending inwardly from one side edge of the flap and money?covering the slide'rsand having inspection openings for observing thedigits on the sliders and parallel slots each permitting access toeleven notches-on one serrated edge ofone slider, each end of each ofthe slots being provided with return extensions to expose two notches onthe other serrated edge of the adjacent slider, a reversible flapadapted to cover the return extensions at eitherend of the parallelslots, the flap being provided with inspection openings adapted toregister with the inspection openings on the front plate when the flapis in one position, and a sheetmetal guide-plate having a pair ofoppositely directed spring guiding-fingers struck out from one face ofthe plate and integral therewith, the sliders having two rows ofrearwardly projecting prongs providing a guiding channel to embrace thespring fingers on the plate and being pressed thereby against the backside of the front plate.

13. A. computing machine having reciprocating sliders, each havingserrated edges and provided with the digits 9, 6, l, 6, 5, t, 3, 2, 1,O, the digit 9 being at one end of the slider, the slider being blankbelow the O, a front plate covering the sliders and having slots forpermitting access to notches on the lateral edges of the sliders forcarrying forward mathematical sums, inspection openings for observingthe digits on each of the sliders, the disappearance from behind one ofsaid openings of the slider-end having the digit ,9 providing a visiblesignal to indicate to the operator that the position of the slidersshould be changed in a predetermined manner to indicate the correctresult, the appearance through one of the inspection openings of theblank space on a slider providing a visible signal to indicate to theoperator that the position of the sliders should-she changed in anotherpredetermined manner to indicate the correct result, and a sheet metalguide-plate having a pair of oppositely directed spring guidingfingersstruck out from one face of the plate and integral therewith, thesliders having two rows of rearwardly projecting prongs providing aguiding channel to embrace the spring fingers on the plate and beingpressed thereby against the back side of the front plate.

Signed at Berlin 011 the 29 day of September, 1924;. LUCIE THOMAS.

